Quantitative analysis of intermolecular interactions in 2,2′-((4-bromophenyl)methylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-l-one): insights from crystal structure, PIXEL, Hirshfeld surfaces and QTAIM analysis

The crystallographic study of 2,2'-((4-bromophenyl)methylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-one) reveals that the compound crystallizes in the centrosymmetric space group P2(1)/c. In the solid state, the structure of the title compound exhibits two strong intramolecular O-H center dot center dot center dot O hydrogen bonding interactions. Further, molecules of the title compound are self-assembled by weak intermolecular C-H center dot center dot center dot O, pi center dot center dot center dot pi and H center dot center dot center dot H and C-H center dot center dot center dot Br contacts. Various intermolecular interaction that exist in the crystal structure and their energetics are quantified using PIXEL, DFT and QTAIM analyses. Six different motifs are identified from the PIXEL calculation. Lattice energy calculation suggests that the dispersion energy has the highest contribution for the crystal formation. The relative contributions of various intermolecular contacts in the title compound and its closely related analogs are evaluated using Hirshfeld surface analysis and the decomposed fingerprint plots. The common packing features exist between the title compound and its related analogs are identified. The quantitative molecular electrostatic potential surface diagram depicts the potential binding sites which are in good agreement with the crystal structure of the title compound. The structures of title compound in gas and solvent phases are compared with the experimental structure and reveals that they are superimposed very well. The vibrational modes of the monomer and four most stabilized dimers are characterized using both the experimental and DFT calculations. The UV-Vis spectrum is calculated using time dependent-DFT (TD-DFT) method and compared with experimental spectrum. The results indicate that the calculated energy of absorbance and oscillator strength correlate well with the experimental data.